Piston



March 31. 1925. 1,531,721

J. WIYLLIAMS ET AL PISTON Filed Dec. 11, 1924 Patented Man 31, 1925.

JOHN WILLIAMS AND JUDSON WILLIAMS, 0]? PHILADELPHIA, PENNSYLVANIA.

rrs'ron.

Application filed December 11, 1924. Serial No. 755,247.

To all whom it may concern:

Be it known that we, J OHN WILLIAMS and J UnsoN WILLIAMS, citizens ofthe Umted States, residing at Philadelphia, in the county ofPhiladelphia and State of Pennsylvania, have. invented certain new anduseful Improvements in Pistons, of which the following is aspecification.

This invention relates to an improved engine piston and seeks, amongother objects,

, to provide a piston wherein, in use, looseness of the piston will, toall intents and purposes, be permanently overcome. The invention seeks,as'a further ob ect,

to provide a iston wherein so-called piston slap will be ellminated andthe usual troubles resulting therefrom thus overcome.

. And the invention seeks, as a still further object, tov provide anover-size self-conforming piston which will take up wear as wear occursWhile undue friction will be avoided.

Other and incidental objects will appear hereinafter.

In the accompanying drawings:

Figure 1 is a vertical sectional view on the line 1--1 of-Figure 2,looking in the direction indicated by the arrows, a cylinder being shownin dotted lines.

Figure 2 is a vertical sectional view on the line 22 of Figure 1,looking in the direction indicated by the arrows, this view illustratingthe iston in position within a conventional cy inder,

Fi re 3 is a horizontal sectional view on the hue 33 of Figure 2,looking in the direction indicated b the arrows.

In accordance with the present invention,

'. the improved piston is formed with a head 10 which is providedinternally with reinforcing ribs 11 and externally with an approvednumber of ring ooves 12 to receive expansible rings 13 1n the usualmanner. The rin are conventionally shown. Depending from the head is acyllndrical skirt 14 integral with the head and formed in the skirt atthe base of. the head are oppositely disposed segmental slots 15defining intervening webs 16 therebetween. At said webs, the skirt isformed with arallel side plates 17 which extend in chordhl relation tothe circumference of the skirt, being free at their lower edges, andformed on said plates are 1 oppositely disposed wrist pin bearings 18and opens at its lower end through the lower edge of the skirt while -atits upper end, the slot opens into one of the grooves 15. The skirt isthus severed throughout its length and it is now to be observed that themetal from which the piston is formed is resilient so that the skirt isthus adapted to flex. In

other words, the skirt may be contracted in circumference and thusv brouht under tension,'when'the skirt will tend to expand to its normaldiameter.- Any approved metal or alloy may be empl yed in forming thepiston, provided the necessary resiliency is present. Formed in theskirt 14 near its lower end is I an external annular oil groove 21.

In Figure 1 of the drawings, we have shown a conventional cylinder indotted lines at 22, and attention is now directed-to the fact that theskirt 14 of the piston is tapered from anexternal over-size diameter atthe lower end of the skirt to substantially cylinder size diameter atthe upper end of the skirt so that the piston is thus of truncatedcone-shape. The point is stressed that the Hare of the skirt is overcylinder size as distinguished from under cylinder size. In practice,the piston is first formed in the rough. when the skirt is turned orground externally to impart the desired taper thereto. The taper maystart at a few thousandths of an inch over cylinder size at the lowerend of the skirt and stop at substantially cylinder size at the level ofthe lower edges of the slots 15, or, as has been found expedient in somecases, the taper may stop at substantially cylinder size at a levelclose below said slots. In any event, the skirt is externally tapered atits lower end portion and the flare thus imparted to the skirt is overcylinder size. In Figure 1 of the drawings, the flare is exaggerated tomore clearly bring out the feature. 'In Figures 2 and 3 of the drawings,we have shown the piston disposed within a conventional cylinder 1 23and, as will be observed, the lower end portion of the skirt approached,the contraction of the skirt I gradually increases in proportion totheare of the skirt and accordingly, the pressure of the skirt against thewall of the cylinder gradually increases from' the upper end of theskirt to the lower end thereof. A- tight fit between the piston andcylinder is thus effected and as the wall of the cylinder and the skirtof the piston wear, the skirt will, of course, expand to take up suchwear so that the tight fit between thepiston and cylinder will bemaintained. In this connection, it is to be noted that a piston having astraight split skirt over cylinder size would not accomplish the objectsof the invention for the reason that such a skirt, when contracted tocylinder size at its upper end, by the insertion of the piston in acylinder, would be flexed to under cylinder size at its lower end. Thisis due to the fact that the skirt is necessarily rein forced and bracedat its upper end by the piston head while the lower-end of the skirt isfree. Accordingly, a pressure at the top of the skirt suflicient tocontract a straight skirt to cylinder size, would cause an over flexingof the lower end of the skirt. This result is avoided in the presentinvention, by tapering the skirt exterio-rly toward its upper end sothat the over size lower end portion of the skirt is pressed against thecylinder.

that after the piston is wornin, as it is commonl called, the pistonbecomes accommodate to the exact shape of the inner surface of the clinder with the result that the piston will t en travel smoothly withinthe I However, no looseness is de-. veloped and the piston still expandsto provide a tight joint with the cylinder wall.

Furthermore, it has been discovered that when the improved piston-isinstalled in an old cylinder which has become more or less worn, thepiston will, after a short period of use conform to the shape of theworn cylinder and form a, tight joint therewith throu bout the innercircumference of the cylin er. We thus provide a iston which will.eliminate the various'trou les now experienced from loose or wornpistons.

Having thus described theinvention, what we claim is: y s

A piston comprising a'head having a resilient skirt provided with wristpin bosses and being disconnected from the head between said bosses, theskirt beingprovided with a split extending from the lower end of theskirt above the plane of the axes of said bosses and being externallytapered from an over cylinder size diameter at its lower end toward itsupper end whereby when the piston is inserted in a cylinder and theskirt is compressed by the cylinder wall the external surface of theskirt will bear against the cylinder wall substantially unifor y.

tures.

In testimony whereof we aflix our signa-

